Mass flow sensors basically use only two tube shapes, namely, on the one hand, straight measuring tubes and, on the other hand, arbitrarily bent or even twisted measuring-tube loops, among which the U-shaped loops are the preferred tube shapes. For reasons of symmetry, two straight measuring tubes extending parallel to each other in two parallel planes in a state of rest, or corresponding tube loops, are generally used.
Regarding one of the two variants, namely the one using two parallel straight tubes, reference is made, by way of example, to applicant's U.S. Pat. Nos. 4,768,384 and 4,793,191. The other variant, using two parallel U-shaped tube loops, is disclosed, for example, in U.S. Pat. No. 4,127,028.
WO-A-87/06691 discloses a Coriolis-type mass flow sensor in which the ends of at least one measuring tube are inserted in bores of inlet-side and outlet-side transition pieces, respectively, and fixed therein by welding, soldering, or brazing at the front and rear sides, cf. the material bulges that are visibile in some of the figures. The transition pieces are fixed in an external support.